Yes - oil pressure again

[beljames]

Kind of prompting a survey with this really. To let me know how much I should worry...

The old dog starts up with a splendid oil pressure, leaping to about 50-60 psi.

On idle she hovers patiently around 15.

When she warms up she'll pootle around at about 20-30 psi.

All sounds pretty rosy so far. However...

When she's been driven around a lot and got all nice and hot, the oil pressure dips below that magical 15 on idle. Difficult to say to where, because the gauge is wonderfully vague. Is it below 10? Well, possibly - if the half-way between 0 & 15 is 7.5.

How does this compare to your toys? I am well aware what low oil pressure can do but I'm interested in how we compare.

Oh - and finally, water pumps. Mine has started to rattle. I know its the water-pump because a well aimed shot of spray-grease shuts it up. But not for long! Looks easy enough ot replace. Any pitfalls?

>>> Edited by beljames on Monday 8th April 19:16

[ATG]

Oil pressure sounds similar to mine when it was on 0-40 Mobil. When hot, this stuff gets very runny. In an "interesting experiment" I heated up some engine oil in a saucepan and the change in viscosity was really, really marked when it got H-O-T. Now I am no expert, but I can't see that the drop in pressure in itself should be a problem so long as the drop is due to the oil becoming less viscous.

[beljames]

Interesting. What do you run now, and has it solved your problem?

[ATG]

Ah yes ... well ... embarassing ... dunno. Had the car serviced a little while ago and forgot to ask what they filled it with.

So far doesn't need a top up. Get the impression they have used something more viscous as pressure generally reads a little higher and doesn't drop as far as before when things get hot. But they also overfilled it slightly, so this might be the cause (which would be a bit worrying).

I've recently (finally) got a temp guage running from the sump plug. tends to indicate the oil continues to get hotter for a while after the fans have cut in, even if the coolant temperature has been stabilised btwn 90/95C. This would seem to be consistent with the oil pressure continuing to drop after the fans have cut in.

[Marshy]

ATG, did you get the extra gauge mounted in the dash, or have you done something else? Did you do it yourself or get someone else to do it?

[.mark]

Fernhurst now use Valvoline 5W50, I'm told someone came round and told them Mobil 1 was too thin, espacially if you are a trackday person.

[ATG]

Home made. Not mounted in the dash yet. Initially in a bracket to the right of the steering wheel. Bracket sharing dashboard bolt. Guage is an ammeter. Sensor is a temp sender screwed into the sump plug (bought from Halfords so they couldn't provide a datasheet ... tossers). I've knocked up a circuit to match the sender to the ammeter and its in a box behind the radio.

p.s. I assume slagging off Halfords is exempt from the "naming and shaming" rule, as it isn't exactly news.